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A Brief Introduction

The Twonker is a MIDI Plugin that allows a digital piano (or any MIDI instrument) to play tones from the Overtone Series (also known as the Harmonic Series). It is designed to run within most Digital Audio Workstations as a Synth Plugin on Windows, MacOS, and Linux.

Latest News

[2018/2/12] Twonker v1.0.0 Released!

It's finally here! The first stable release of The Twonker.

Download The Twonker automatically according to your operating system or manually from SourceForge.Net.

Further Reading

What are Overtones?

When a length of string (or a column of air) is made to vibrate it produces a pitch. This initial pitch is called the Fundamental.

While the string is vibrating at the Fundamental frequency, the string simultaneously vibrates at many other frequencies as well. The pattern of frequencies is always the same and is based on the frequency of the Fundamental itself.

In addition to the Fundamental, the string vibrates at a second frequency which is one-half the wavelength of the Fundamental (or double in pitch; which is an octave). This second frequency is called the First Overtone. The pattern repeats as the string also vibrates at another frequency which is one-third the wavelength of the First Overtone. This third frequency is called the Second Overtone.

The process continues indefinitely, diminishing in volume as the pattern repeats. The pattern of notes is referred to as the Overtone Series.


This is one way to visualize the Fundamental and the first three Overtones from the Series. The Fundamental is represented at the top, and each successive overtone moving down-wards is visualized with respect to it's relative frequency with the Fundamental.

Each individual frequency is vibrating with all the others at the same time. All musical instruments generate the same pattern of overtones. However, different instruments will accentuate and lessen different overtones in their respective series. This is why a clarinet sounds different from a flute when they play the same tone at the same volume. The difference is in the relative volumes of their Overtone Series.

What is Equal Temperament?

Equal Temperament is a system of musical tuning in which each octave is divided into twelve equal-sized intervals. A typical piano is an example of an Equal Tempered instrument. Each octave is divided into twelve half-steps; each being the same size.

In Equal Temperament, changing keys is easy and does not require that the instrument be retuned. For example, the C Chromatic Scale uses the same twelve tones as the G Chromatic Scale.

What is the "Just Scale"?

The Just Scale is a scale built on the Overtone Series. In comparison with Equal Temperament however, the Just Scale does not have equal-sized intervals.

Given that the intervals between tones in the Just Scale are not equal-sized, Just Scales contain totally different tones when compared with each other. This makes changing the piano's key impossible.

In order to allow multiple keys in Just Temperament, you would need to build twelve pianos; each tuned to a different Fundamental. To switch Just Scales from C to G, run over to the G piano and wail away.

Enter: The Twonker

The Twonker allows a musician to play overtones in a predictable and flexible manner, using a regular MIDI-based keyboard. In essence, it behaves like twelve different pianos tuned to twelve different Just Scales. You "change the piano" by simply choosing a new Fundamental and otherwise playing normally.

Further Reading